The present invention relates to a seal for an anti-friction bearing. The seal includes lips or ridges which engage at least one of the rings of the bearing to effect the seal.
Federal Republic of Germany No. AS 24 14 643 discloses a multi-lip shaft seal in which two radially acting sealing lips are connected to each other by an axially-extending membrane or neck part. This avoids undesired influence of the sealing lips with respect to each other upon the tilting of the shaft.
Federal Republic of Germany No. OS 19 39 597 discloses a double-lip seal in which two radially directed sealing lips point in the same direction. This arrangement requires a large amount of axial space. In known seals, furthermore, inaccuracies resulting from tolerances do not result in unambiguous application forces. The seals, shown in these disclosures in half cross-section, must be seen as ring-shaped parts. The application force of the sealing lips or sealing ridges results from the amount of their widening upon being pulled onto the inner ring or onto the shaft respectively and from the bending up or deformation of the sealing axial membrane upon installation. Since the two cannot be exactly determined, the application force, and thus the moment of friction, is also imprecise. For this reason, a spring which presses one of the sealing lips against the shaft has also been suggested in the seal in Federal Republic of Germany No. AS 24 14 634. In this way, to be sure, the application force and the moment of friction are also increased.
These are cases in which one sealing lip on the seal is sufficient to protect the bearing from the penetration of dirt. However, as a result of axial clearance, for instance in the case of deep-groove ball bearings, there is a disadvantage that axial movement of the shaft can take place. It corrosion has set in alongside the place of travel of the seal, under environmental conditions which are unfavorable when the bearing is at a standstill, and if upon axial movement, the corrosion has moved to below the sealing lip, this reduces the life of the seal and of the bearing.